Heat training has evolved into a mandatory component of professional cycling, with WorldTour teams increasingly utilizing sauna sessions, indoor heat-stress workouts, and environmental acclimation to boost blood plasma volume and thermoregulation. As global temperatures rise, these protocols are now considered essential for maintaining high-intensity performance during extreme weather events in races like the Tour de France.
The Physiological Basis for Heat Acclimation
Heat training operates on the principle that controlled thermal stress triggers specific cardiovascular adaptations. According to research, exposing the body to repeated heat stress increases blood plasma volume. This expansion helps the body regulate core temperature more efficiently, lowers heart rate during exertion, and improves overall sweat rates.
Furthermore, this physiological stress can stimulate the release of natural erythropoietin (EPO), which contributes to increased hemoglobin mass. For endurance athletes, these adaptations mimic some benefits of altitude training, leading to improved VO2 max and greater exercise efficiency. Teams now view these sessions as a "poor man’s altitude," providing a performance edge that is critical when racing in temperatures exceeding 35°C.
Modern Implementation in the WorldTour
Professional teams have moved away from reactive cooling methods—such as ice socks or slushies—toward proactive physiological preparation. Strategies generally fall into two categories:
- Active Heat Training: Riders perform low-intensity workouts indoors while wearing heavy clothing, hazmat-style suits, or winter gear to force the body to shed heat.
- Passive Heat Training: Riders spend time in saunas or high-temperature baths following standard training sessions.
"Heat training is definitely a much bigger part of our preparation now," said Stephen Barrett, head of performance at Decathlon AG2R La Mondiale, in an interview with Velo. Barrett noted that teams are seeing a positive impact on rider tolerance, resulting in fewer heat-related performance issues during recent Grand Tours.
Monitoring and Data Precision
To prevent the risks associated with overheating, teams rely on precise monitoring. Many squads, including UAE Team Emirates, Lidl-Trek, and Soudal Quick-Step, utilize CORE temperature sensors. These devices provide real-time data on core body temperature, allowing coaches to ensure riders reach the necessary threshold to trigger physiological adaptation without crossing into dangerous territory.
Other teams prefer traditional methods, such as internal temperature pills or monitoring the Rate of Perceived Exertion (RPE). Regardless of the tracking method, the consensus among performance staff is that these protocols are now a non-negotiable aspect of the training calendar.
Strategic Timing and Future Outlook
The current best practice for heat acclimation involves 10 to 14 sessions completed over a two-to-three-week block. Teams typically schedule these sessions before early-season desert races and again immediately preceding mid-summer events.
When paired with altitude camps, heat training can serve a dual purpose. According to team performance experts, heat training before altitude exposure helps prepare the body for the stress of thin air, while post-altitude heat training can help extend the physiological benefits of the hypoxic environment. As the climate continues to shift, the integration of these heat-stress protocols is expected to remain a permanent fixture in the pursuit of marginal gains at the highest level of cycling.
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